Table 2 The Newcastle-Ottawa Scale for assessing the quality of case-control studies
Study included | Case defined adequately | Represent-ativeness of the cases | Community controls | Controls have no history of the outcome | Study controls for age | Study controls for sex | Ascertainment of exposure with secure record | Ascertainment of exposure with structured interview where blind to case/control status | Same method of ascertainment for cases and controls | Same non-response rate for both groups | Total score |
|---|---|---|---|---|---|---|---|---|---|---|---|
Zhang 2010 Guangxi | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 9 |
Zhang 2010 Beijing | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 8 |
Zhang 2010 Jiangsu | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 8 |
Zhang 2010 Guangdong | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 8 |
Zhang 2010 Shanghai | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 7 |
Hu 2012 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 9 |
Li 2012 Central | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 8 |
Li 2012 Southern | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 8 |
Sawai 2012 Japan1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 7 |
Sawai 2012 Japan2 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 6 |
Sawai 2012 Korea | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 7 |
Sawai 2012 Hong Kong | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 6 |
Chen 2013 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 9 |
Jiang 2013 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 7 |
Sopipong 2013 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | 6 |
Su 2014 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 9 |
Pan 2015 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 7 |
Chen 2016 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 7 |